Okay folks, I have a dilemma. My computer is over half a decade old, and sorely needs to be replaced. I know relatively little about hardware, but I want to build a computer from parts, so I can have more control over what I put in the machine, and can do so at a lower cost. I've got the resources and expertise to be able to assemble the thing, but I first need help selecting parts. I'm aiming to be under $999 in parts, preferably in the vicinity of $600-800.
When looking over parts, I'm considering that I do a fair bit of gaming, so I'd like it to be fairly powerful, with a reasonable storage capacity. My first priority is general processing power. Second, I'd like mid-to-high graphics capabilities. Third, I want reasonable storage capacity (150Gb has been fine in the past, but I know that's pretty skimpy these days). I don't necessarily want top-of-the-line components, but I'd like to use generally solid parts all around, from the power supply and cables, to the motherboard and hardrive, etc. Also, I intend to do LAN parties and whatnot with this thing, so portability and durability are plusses. I'm intending to run XP (possibly Windows 7) ideally with a little Ubuntu partition too, if it's relevant.
Lacking personal experience with the science of Computer Frankensteining, I come to you guys for advice. If you've got a new computer, what brands and specific parts do you recomend and/or trust? What services are best to look for parts on? How best can I go about making a fairly inexpensive, but modern machine?